Methods of treating lost circulation zones

ABSTRACT

A method of treating a lost circulation zone may include positioning a cured lost circulation material composition in the lost circulation zone of a subterranean natural resource well to produce a barrier operable to mitigate wellbore fluids from passing into the lost circulation zone. The cured lost circulation material composition may be a foam comprising a gas phase and a liquid phase. The cured lost circulation material composition may include a cured bisphenol epoxy resin, one or more surfactants positioned at the interface of the liquid phase and the gas phase of the foam and carbon dioxide in the gas phase of the foam. The cured bisphenol epoxy resin may be a reaction product of a bisphenol epoxy resin system including uncured bisphenol epoxy resin, one or more curing agents, and optionally, a diluent. The carbon dioxide may be a reaction product of one or more carbon dioxide gas-generating compounds.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to naturalresource well drilling and, more specifically, to methods for treatinglost circulation zones of a wellbores.

BACKGROUND

Extracting subterranean hydrocarbons may require drilling a hole fromthe surface to the subterranean geological formation housing thehydrocarbons. Specialized drilling techniques and materials are utilizedto form the wellbore hole and extract the hydrocarbons. Specializedmaterials utilized in drilling operations include drilling fluids andmaterials for sealing the casing-casing annulus of the wellbore, whichmay be formulated for specific downhole conditions. A wellbore is a holethat extends from the surface to a location below the surface to permitaccess to hydrocarbon-bearing subterranean formations. The wellborecontains at least a portion of a fluid conduit that links the interiorof the wellbore to the surface. The fluid conduit connecting theinterior of the wellbore to the surface may be capable of permittingregulated fluid flow from the interior of the wellbore to the surfaceand may permit access between equipment on the surface and the interiorof the wellbore. The fluid conduit may be defined by one or more tubularstrings, such as casings, inserted into the wellbore and secured in thewellbore.

During drilling of a wellbore, cementing the wellbore, or both, lostcirculation zones may be encountered which result in loss of drillingfluids, cementing compositions, or other fluids. In a lost circulationzone, the drilling fluids, cement compositions, or other fluids flow outof the wellbore and into the surrounding formation. Depending on theextent of fluid volume losses, lost circulation is classified as seepageloss, moderate loss, or severe loss. For oil-based fluids, losses of10-30 barrels per hour are considered moderate, and losses greater than30 barrels per hour are considered severe. For water-based fluids,losses between 25 and 100 barrels are considered moderate, and lossesgreater than 100 barrels are considered severe. For severe losses, thedimensions of the lost circulation zones cannot be estimated which makesit difficult to design loss circulation treatment pills based on thesized particles. Lost circulation zones may increase the cost of thewell through increased material costs to replace lost fluids anddowntime to remediate the lost circulation zone.

SUMMARY

Lost circulation zones may be remediated by introducing a lostcirculation material (referred to sometimes herein as an “LCM”) into thelost circulation zone to seal off the lost circulation zone to preventfurther fluid loss. An ongoing need exists for lost circulationmaterials for treating lost circulation zones encountered duringresource well drilling. According to one or more embodiments describedherein, LCM compositions may comprise cured bisphenol epoxy resins,surfactants, and carbon dioxide. The LCM compositions may form a foamthat creates a barrier to prevent drilling fluids at a pressure greaterthan the formation pressure from flowing out of the wellbore and intothe formation. One or more surfactants may be positioned at theinterface of a liquid phase and a gas phase of the foam. Carbon dioxidemay be in the gas phase of the foam. The cured bisphenol epoxy resin maybe a reaction product of a bisphenol epoxy resin system, which comprisesuncured bisphenol epoxy resin, a curing agent, and optionally, adiluent. Volume adaptability is introduced in the LCM compositionsthrough in-situ generation of carbon dioxide gas as a result of thedecomposition of a carbon dioxide gas-generating compound duringformation of the LCM compositions. The LCM compositions disclosed hereinmay exhibit greater effectiveness at preventing fluid loss in aformation due to volume expansion of the LCM composition upon curingcompared to conventional, non-expanding LCM compositions.

In one or more embodiments, a method of treating a lost circulation zonemay comprise positioning a cured lost circulation material compositionin the lost circulation zone of a subterranean natural resource well toproduce a barrier operable to mitigate wellbore fluids from passing intothe lost circulation zone. The cured lost circulation materialcomposition may be a foam comprising a gas phase and a liquid phase. Thecured lost circulation material composition may comprise a curedbisphenol epoxy resin, one or more surfactants positioned at theinterface of the liquid phase and the gas phase of the foam, and carbondioxide in the gas phase of the foam. The cured bisphenol epoxy resinmay be a reaction product of a bisphenol epoxy resin system comprisinguncured bisphenol epoxy resin, one or more curing agents, andoptionally, a diluent. The carbon dioxide may be a reaction product ofone or more carbon dioxide gas-generating compounds.

Additional features and advantages of the described embodiments will beset forth in the description of drawings and detailed description whichfollows, and in part will be readily apparent to those skilled in theart from that description or recognized by practicing the describedembodiments, including the detailed description which follows as well asthe claims.

DESCRIPTION OF DRAWINGS

The following detailed description of specific embodiments of thepresent disclosure can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 shows an image of a comparative example epoxy resin composition;and

FIGS. 2A and 2B show images of example epoxy resin compositions,according to one or more embodiments described herein.

Reference will now be made in greater detail to various embodiments,some embodiments of which are illustrated in the accompanying drawings.Whenever possible, the same reference numerals will be used throughoutthe drawings to refer to the same or similar parts.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed to lost circulationmaterial (LCM) compositions. The LCM compositions of the presentdisclosure, used for treating lost circulation zones in subterraneannatural resource wells, may comprise a cured bisphenol epoxy resin, asurfactant, and carbon dioxide. The LCM compositions may be a foam,comprising a gas phase and liquid phase wherein the surfactants arepositioned at the interface of the liquid phase and the gas phase of thefoam, and the carbon dioxide is in the gas phase of the foam. As usedthroughout this disclosure, the term “foam” may refer to a mass of smallbubbles formed on or in a liquid. Volume adaptability is introduced inthe LCM compositions through in situ generation of carbon dioxide gasdue to decomposition of a carbon dioxide gas-generating compound underdownhole conditions, such as elevated temperatures. The expandablenature of the LCM compositions allows the LCM compositions to adapt involume to effectively seal a wide range of fractures with unknowndimensions in subterranean formations.

As used throughout this disclosure, the term “lost circulation zone” mayrefer to an area encountered during drilling operations where the volumeof drilling fluid returning to the surface is less than the volume ofdrilling fluid introduced to the wellbore. The lost circulation zone maybe due to any kind of opening between the wellbore and the subterraneanformation. As used throughout this disclosure, the term “subterraneannatural resource well” may refer to a geologic region containinghydrocarbons, such as crude oil, hydrocarbon gases, or both, which maybe extracted from the subterranean geologic region. Lost circulationzones that can be addressed by LCM compositions described herein and mayrange from seepage loss to complete fluid loss. As used throughout thisdisclosure, the term “lost circulation material” may refer to anymaterial that may be used to treat a lost circulation zone.

The embodiments described herein may have advantages over conventionallost circulation remediation techniques. For example, cementcompositions, such as reduced-cure-time cements, have been used to treatlost circulation zones to seal off the lost circulation zone from thewellbore. However, during subsequent continued drilling of the wellboreand hydrocarbon production using the well, conventional cementcompositions injected and cured to isolate lost circulation zones may besubjected to ongoing temperature and pressure cycling. This temperatureand pressure cycling may cause micro-cracks to form in the curedcements. Fluids, such as gas or liquids, may migrate through thesemicro-cracks, eventually resulting in additional loss of fluids to thelost circulation zone.

As described herein, epoxy resin-based materials may be incorporatedinto LCM compositions for treating lost circulation zones, which mayreduce or eliminate the cracking in conventional lost circulation zonetreatments caused by continued temperature and pressure cycling. As usedthroughout this disclosure, the term “epoxy resin” may refer to both aprepolymer and polymer containing epoxide groups. The epoxy resin basedmaterials, once cured, may be more resistant to formation ofmicro-cracks caused by thermal and pressure cycling of the wellborecompared to conventional cements. However, one reason why lostcirculation is difficult to remedy is lack of precise information on thedimensions of loss circulation areas, which can range frommicrofractures to vugular zones, thus leading to an improper selectionof suitable plugging materials that can adapt, in both volume and shape,to effectively plug a wide range of fractures with unknown dimensions.Traditional lost circulation materials, such as non-reactive particulateor fiber based or settable fluids, when applied in insufficientquantities, cannot effectively seal a high permeability zone. Thus,there is a need for a composition that is adaptable in volume in orderto effectively seal a wide range of fractures with unknown dimensions.

The embodiments described herein of the LCM compositions may provide afoamed, space-filling epoxy resin, capable of plugging the pores of theformation to reduce fluid loss more effectively than conventional,non-foaming LCM compositions. The foamed LCM compositions of the presentdisclosure can be used to mitigate (reduce or eliminate) losscirculation in a subterranean formation, such as a wellbore. Thus, alsoprovide in the present disclosure are methods of controlling losscirculation using the LCM compositions. In some embodiments, the LCMcompositions decreases the amount of LCM required to plug vugular zonesas compared to traditional lost circulation materials that are not ableto expand and adapt in volume. Thus, the LCM compositions of the presentdisclosure can be used to cure the losses in vugular zones while usingless material than traditional LCMs.

According to one or more aspects of the present disclosure, the LCMcompositions for treating lost circulation zones in a wellbore maycomprise a cured bisphenol epoxy resin, wherein the cured bisphenolepoxy resin is a reaction product of a bisphenol epoxy resin system. Asused in this disclosure, the term “epoxy resin system” may refer to theconstituents that react to form the cured epoxy resin and may comprisebut are not limited to the epoxy resins, reactive and non-reactivediluents, and curing agents. The “epoxy resin system” may generallyexclude weighting materials, emulsifiers, and components and additivesthat do not participate in the polymerization reaction of the epoxysystem. In the present disclosure, surfactants are treated as separateconstituents of the LCM compositions but may be considered part of theepoxy resin system in some embodiments. As used throughout thisdisclosure, the term “cured epoxy resin” may refer to a polymercontaining epoxide groups after crosslinking.

In some embodiments, the cured epoxy resin of the LCM composition maycomprise bisphenol-based epoxy resins such as but not limited to,bisphenol-A-based epoxy resins, bisphenol-F-based epoxy resins, orcombinations thereof.

In some embodiments, the LCM composition may comprise a plurality ofcured epoxy resins. The LCM composition may comprise a combination oftwo or more of bisphenol-A-based epoxy resins or bisphenol-F-based epoxyresins. In one or more embodiments, the cured epoxy resin of the LCMcomposition may comprise two or more of bisphenol-A-epichlorohydrinepoxy resin,2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxiraneepoxy resin, or combinations of these.

In some embodiments, the LCM composition comprises a cured bisphenolepoxy resin that comprises bisphenol-A-epichlorohydrin epoxy resin,2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane, orcombinations of these.

The cured epoxy resin of the LCM composition may have an epoxy value offrom 4.5 epoxy equivalents per kilogram of the epoxy resin to 5.5 epoxyequivalents per kilogram of the epoxy resin. The epoxy equivalent weightof an epoxy resin is the weight of the epoxy resin in grams thatcontains one equivalent weight of epoxy. The epoxy equivalent weight ofthe epoxy resin is equal to the molecular weight of the epoxy resindivided by the average number of epoxy groups in the epoxy resin. Theepoxy resins may have an epoxy equivalent weight of from 170 to 350grams of resin per epoxy equivalent (g/eq). The epoxy value and epoxyequivalent weight of an epoxy resin may be determined according toASTM-D1652. Other methods of determining the epoxy value and epoxyequivalent weight of the epoxy resin may also be used to determine theepoxy value or epoxy equivalent weight of the epoxy resin.

In some embodiments, the cured epoxy resin of the LCM composition may bemodified with a reactive diluent. The type and amount of reactivediluent may influence the flexibility, hardness, chemical resistance,mechanical properties, plasticizing effect, reactivity, crosslinkingdensity, or other properties of the epoxy resin. The reactive diluentcan be a non-functional, mono-functional, di-functional, ormulti-functional reactive diluent. For example, a non-functionalreactive diluent does not have an epoxide functional group. As used inrelation to reactive diluents, the term “functional” refers to thereactive diluent having at least one epoxide functional group. Afunctional reactive diluent may have one, two, three, or more than threeepoxide functional groups. The term “non-functional”, as used inrelation to reactive diluents, refers to a reactive diluent that doesnot have at least one epoxide functional group. Thus, a non-functionalreactive diluent does not have at least one epoxide functional group,but may still participate in at least one chemical reaction duringcross-linking of the epoxide resin. The term “non-reactive diluent” mayrefer to a diluent that does not participate in a chemical reactionduring cross-linking of the epoxy resin. Examples of reactive diluentsmay comprise glycidyl ethers. Glycidyl ethers may comprise alkylglycidyl ethers, aromatic glycidyl ethers, or both. Glycidyl ethers mayhave chemical formula (I):

R¹—O—CH₂—(C₂H₃O)  (I)

where R¹ may be a linear, branched, cyclic, or aromatic hydrocarbylhaving from 4 to 24 carbon atoms, such as from 4 to 20, from 4 to 16,from 4 to 12, from 4 to 8, from 6 to 24, from 6 to 20, from 6 to 16,from 6 to 12, or from 12 to 14 carbon atoms. In some embodiments, R¹ maybe a branched, linear, or cyclic alkyl. In some embodiments, R¹ maycomprise one or more substituted or unsubstituted aromatic rings.

In some embodiments, the diluent may comprise diglycidyl ethers.Diglycidyl ethers may have chemical formula (II):

(OC₂H₃)—CH₂—O—R²—O—CH₂—(C₂H₃O)  (II)

where R² may be a linear, branched, cyclic, or aromatic hydrocarbylhaving from 4 to 24 carbon atoms, such as from 4 to 20, from 4 to 16,from 4 to 12, from 4 to 8, from 6 to 24, from 6 to 20, from 6 to 16,from 6 to 12, or from 12 to 14 carbon atoms. In some embodiments, R² maycomprise one or more substituted or unsubstituted aromatic rings. Insome embodiments, R² may be an alkyl group or cycloaklyl group. Forexample, in some embodiments, the diluent may comprise 1,6-hexanedioldiglycidyl ether, which has chemical formula (III):

(OC₂H₃)—CH₂—O—C₆H₁₂—O—CH₂—(C₂H₃O)  (III)

In some embodiments, the epoxy resin of the LCM composition may comprisea diluent having the formula (IV):

R³—O—CH₂—(C₂H₃O)  (IV)

where R³ may be a linear or branched hydrocarbyl having from 12 to 14carbon atoms. R³ may be linear, branched, or cyclic. In someembodiments, R³ may be an alkyl group. In some embodiments, R³ is analkyl group having from 12 to 14 carbon atoms. In some embodiments, theepoxy resin system may comprise a diluent oxirane mono[(C₁₂-C₁₄)-alkyloxy)methyl] derivatives.

In one or more embodiments, the epoxy resin of the LCM composition maycomprise a cured bisphenol epoxy resin. In one or a plurality ofembodiments, the cured bisphenol epoxy resin may bebisphenol-A-(epichlorohydrin) epoxy resin. Thebisphenol-A-epichlorohydrin epoxy resin may refer to an epoxy resin madeby reaction of bisphenol-A and epichlorohydrin. In some embodiments, thebisphenol-A-(epichlorohydrin) epoxy resin may be modified with adiluent. In some embodiments, the epoxy resin may comprise abisphenol-A-(epichlorohydrin) epoxy resin modified with a diluent. Insome embodiments, the cured epoxy resin may comprise abisphenol-A-(epichlorohydrin) epoxy resin with oxirane mono [(C₁₂-C₁₄alkyloxy)methyl] derivatives. The bisphenol-A-(epichlorohydrin) epoxyresin with oxirane mono [(C₁₂-C₁₄)-alkyloxy) methyl] derivatives mayprovide the LCM compositions with improved mechanical and chemicalresistance compared to LCM compositions with thebisphenol-A-(epichlorohydrin) epoxy resin without the reactive diluentoxirane mono [(C₁₂-C₁₄)-alkyloxy) methyl] derivatives.

In one or more embodiments, the epoxy resin comprising thebisphenol-A-(epichlorohydrin) epoxy resin with the reactive diluentoxirane mono [(C₁₂-C₁₄)-alkyloxy) methyl] derivatives may have an epoxyvalue of from 4.76 epoxy equivalents per kilogram of epoxy resin to 5.26epoxy equivalents per kilogram of epoxy resin. The epoxy resincomprising the bisphenol-A-(epichlorohydrin) epoxy resin with thereactive diluent oxirane mono [(C₁₂-C₁₄)-alkyloxy) methyl] derivativesmay have an epoxy equivalent weight of 190 g/eq to 210 g/eq.

In one or more embodiments, the epoxy resin of the LCM composition maycomprise a cured bisphenol epoxy resin. In one or more embodiments, thecured bisphenol epoxy resin may be2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane. The2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxiraneepoxy resin may additionally be modified with a reactive diluent, suchas 1,6 hexanediol diglycidyl ether. In some embodiments, the cured epoxyresin may comprise2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxiraneepoxy resin with the reactive diluent 1,6 hexanediol diglycidyl ether.

As previously noted, the LCM compositions of the present disclosure maycomprise one or more surfactants, wherein the surfactant is positionedat the interface of the liquid phase and the gas phase of the LCMcomposition. As used throughout this disclosure, the term “surfactant”may refer to a substance that reduces the surface tension of a liquid inwhich it is dissolved. Any type of surfactant can be used in the LCMcompositions of the present disclosure, which may comprise, but are notlimited to cationic surfactants, anionic surfactants, amphoteric(zwitterionic) surfactants, nonionic surfactants, and combinationsthereof.

Examples of suitable surfactants that can be used in the LCMcompositions of the present disclosure include, but are not limited to,alkyl polyglycol ethers, alkylaryl polyglycolethers, ethyleneoxide/propylene oxide (EO/PO) block copolymers, fatty acid polyglycolesters, polyglycol ethers of hydroxyl-containing triglycerides (forexample, castor oil), alkylpolyglycosides, fatty esters of glycerol,sorbitol, or pentaerythritol, amine oxides (for example,dodecyldimethylamine oxide), alkyl sulfates, alkyl ether sulfates,sulfonates, for example, alkyl sulfonates and alkylaryl sulfonates,alkali metal salts or ammonium salts of a carboxylic acid orpoly(alkylene glycol) ether carboxylic acid, partial phosphoric estersor the corresponding alkali metal salt or ammonium salt, for example, analkyl and alkaryl phosphate, an alkylether phosphate, or an alkaryletherphosphate, salts of primary, secondary, or tertiary fatty amines,quaternary alkyl- and alkylbenzylammonium salts, alkylpyridinium salts,alkylimidazolinium salts, alkyloxazolinium salts, sultaines (forexample, cocamidopropyl hydroxysultaine), betaines (for example,cocamidopropyl betaine), phosphates (for example, lecithin), andcombinations thereof.

Examples of anionic surfactants that can be used in the LCM compositionsof the present disclosure include, but are not limited to, an alkylsulfate, an alkyl ether sulfate, an alkyl ester sulfonate, an alphaolefin sulfonate, a linear alkyl benzene sulfonate, a branched alkylbenzene sulfonate, a linear dodecylbenzene sulfonate, a brancheddodecylbenzene sulfonate, an alkyl benzene sulfonic acid, adodecylbenzene sulfonic acid, a sulfosuccinate, a sulfated alcohol, anethoxylated sulfated alcohol, an alcohol sulfonate, an ethoxylated andpropoxylated alcohol sulfonate, an alcohol ether sulfate, an ethoxylatedalcohol ether sulfate, a propoxylated alcohol sulfonate, a sulfatednonyl phenol, an ethoxylated and propoxylated sulfated nonyl phenol, asulfated octyl phenol, an ethoxylated and propoxylated sulfated octylphenol, a sulfated dodecyl phenol, and an ethoxylated and propoxylatedsulfated dodecyl phenol. Other anionic surfactants include ammoniumlauryl sulfate, sodium lauryl sulfate (sodium dodecyl sulfate, SLS, orSDS), and related alkyl-ether sulfates sodium laureth sulfate (sodiumlauryl ether sulfate or SLES), sodium myreth sulfate, docusate (dioctylsodium sulfosuccinate), perfluorooctanesulfonate (PFOS),perfluorobutanesulfonate, alkyl-aryl ether phosphates, and alkyl etherphosphates.

Examples of cationic surfactants that can be used in the LCMcompositions of the present disclosure include, but are not limited to,octenidine dihydrochloride, cetrimonium bromide (CTAB), cetylpyridiniumchloride (CPC), benzalkonium chloride (BAC), benzethonium chloride(BZT), dimethyldioctadecylammonium chloride, anddioctadecyldimethylammonium bromide (DODAB).

Examples of amphoteric (zwitterionic) surfactants that can be used inthe LCM compositions of the present disclosure include, but are notlimited to, 3[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate(CHAPS), cocamidopropyl hydroxysultaine, ocamidopropyl betaine,phospholipids, and sphingomyelins. In some embodiments, the surfactantis a hydroxysultaine. In some embodiments, the surfactant iscocamidopropyl hydroxysultaine.

Examples of nonionic surfactants that can be used in the LCMcompositions of the present disclosure include, but are not limited to,long chain alcohols that exhibit surfactant properties, such as cetylalcohol, stearyl alcohol, cetostearyl alcohol, oleyl alcohol, and otherfatty alcohols. Other long chain alcohols with surfactant propertiesinclude polyethylene glycol alkyl ethers, such as octaethylene glycolmonododecyl ether and pentaethylene glycol monododecyl ether;polypropylene glycol alkyl ethers; glucoside alkyl ethers, such as decylglucoside, lauryl glucoside, and octyl glucoside; polyethylene glycoloctylphenyl ethers, such as Triton X-100; polyethylene glycolalkylphenyl ethers, such as nonoxynol-9; glycerol alkyl esters, such asglyceryl laurate; polyoxyethylene glycol sorbitan alkyl esters, such aspolysorbate, sorbitan alkyl esters, cocamide MEA, cocamide DEA,dodecyldimethylamine oxide, block copolymers of polyethylene glycol andpolypropylene glycol, such as poloxamers, and polyethoxylated tallowamine (POEA).

In one or more embodiments, the LCM composition is a cured foamcomprising a gas phase and a liquid phase. In one or more embodiments,carbon dioxide may be in the gas phase of the foam, wherein the carbondioxide is a reaction product of a carbon dioxide gas-generatingcompound.

In one or more embodiments, the LCM compositions may comprise othermodifiers, such as but not limited to cardanol liquid, weighting agents,polyacrylate flow agents, diluents, viscosifiers, retarders, acids, andaccelerators. Modifiers may be added to the LCM composition to modifyone or more properties of the LCM composition, such as but not limitedto viscosity, yield point (YP), plastic viscosity (PV), gel strength,density, or combinations of these.

In some embodiments, the cured bisphenol epoxy resin is a reactionproduct of a bisphenol epoxy resin system, comprising uncured bisphenolepoxy resin, one or more curing agents, and optionally, a diluent.

In some embodiments, the bisphenol epoxy resin system, the surfactants,and the carbon dioxide gas-generating compounds are combined to form alost circulation material (LCM) precursor.

In some embodiments, the LCM precursor further comprises an epoxy resinportion, wherein the epoxy resin portion may comprise from 60 wt. % to100 wt. % uncured bisphenol epoxy resin based on the total weight of theepoxy resin portion of the LCM precursor. As used in this disclosure,the term “epoxy resin portion” refers to the bisphenol epoxy resins andthe diluents of the LCM precursor. The epoxy resin portion includes theepoxy resins and any added reactive or non-reactive diluents. In someembodiments, the epoxy resin portion may comprise from 60 wt. % to 100wt. %, from 60 wt. % to 95 wt. %, from 60 wt. % to 90 wt. %, from 60 wt.% to 88 wt. %, from 60 wt. % to 86 wt. %, from 60 wt. % to 84 wt. %,from 60 wt. % to 82 wt. %, from 60 wt. % to 80 wt. %, from 60 wt. % to78 wt. %, from 60 wt. % to 76 wt. %, from 60 wt. % to 74 wt. %, from 60wt. % to 70 wt. %, from 70 wt. % to 100 wt. %, from 70 wt. % to 95 wt.%, from 70 wt. % to 90 wt. %, from 70 wt. % to 88 wt. %, from 70 wt. %to 86 wt. %, from 70 wt. % to 84 wt. %, from 70 wt. % to 82 wt. %, from70 wt. % to 80 wt. %, from 70 wt. % to 78 wt. %, from 70 wt. % to 76 wt.%, from 70 wt. % to 74 wt. %, from 74 wt. % to 95 wt. %, from 74 wt. %to 90 wt. %, from 74 wt. % to 88 wt. %, from 74 wt. % to 86 wt. %, from74 wt. % to 84 wt. %, from 74 wt. % to 82 wt. %, from 74 wt. % to 80 wt.%, from 74 wt. % to 78 wt. % from 80 wt. % to 100 wt. %, from 80 wt. %to 95 wt. %, from 80 wt. % to 90 wt. %, from 80 wt. % to 88 wt. %, from80 wt. % to 86 wt. %, from 80 wt. % to 84 wt. %, from 84 wt. % to 100wt. %, from 84 wt. % to 95 wt. %, from 84 wt. % to 90 wt. %, from 84 wt.% to 88 wt. %, or from 84 wt. % to 86 wt. % of uncured bisphenol epoxyresin based on the total weight of the epoxy resin portion of the of theLCM precursor. It should be understood that the total weight of theuncured bisphenol epoxy resin of the epoxy resin portion of the LCMprecursor may be in a range formed from any one of the lower bounds forsuch specific total weight described herein to any one of the upperbounds for such specific total weight described herein.

In some embodiments, the epoxy resin portion of the LCM precursor maycomprise from 0 wt. % to 40 wt. % diluent based on the total weight ofthe epoxy resin portion of the LCM precursor. In some embodiments, thediluent may modify one or more of the viscosity, adhesion, theflexibility, or the solvent resistance of the epoxy resin. In someembodiments, the epoxy resin portion may comprise from 0 wt. % to 40 wt.%, from 1 wt. % to 40 wt. %, from 1 wt. % to 35 wt. %, from 1 wt. % to30 wt. %, from 1 wt. % to 25 wt. %, from 1 wt. % to 20 wt. %, from 1 wt.% to 16 wt. %, from 1 wt. % to 14 wt. %, from 1 wt. % to 12 wt. %, from5 wt. % to 40 wt. %, from 5 wt. % to 35 wt. %, from 5 wt. % to 30 wt. %,from 5 wt. % to 25 wt. %, from 5 wt. % to 20 wt. %, from 5 wt. % to 16wt. %, from 5 wt. % to 14 wt. %, from 5 wt. % to 12 wt. %, from 10 wt. %to 40 wt. %, from 10 wt. % to 35 wt. %, from 10 wt. % to 30 wt. %, from10 wt. % to 25 wt. %, from 10 wt. % to 20 wt. %, from 10 wt. % to 16 wt.%, from 10 wt. % to 14 wt. %, from 12 wt. % to 40 wt. %, from 12 wt. %to 35 wt. %, from 12 wt. % to 30 wt. %, from 12 wt. % to 25 wt. %, from12 wt. % to 20 wt. %, from 12 wt. % to 16 wt. %, from 14 wt. % to 40 wt.%, 14 wt. % to 35 wt. %, 14 wt. % to 30 wt. %, 14 wt. % to 25 wt. %,from 14 wt. % to 20 wt. %, from 14 wt. % to 16 wt. %, from 20 wt. % to40 wt. %, from 20 wt. % to 35 wt. %, from 20 wt. % to 30 wt. %, or from20 wt. % to 25 wt. % of the diluent based on the total weight of theepoxy resin portion of the LCM precursor. It should be understood thatthe total weight of the diluent of the epoxy resin portion of the LCMprecursor may be in a range formed from any one of the lower bounds forsuch specific total weight described herein to any one of the upperbounds for such specific total weight described herein.

In some embodiments, the uncured bisphenol epoxy resin of the LCMprecursor is bisphenol-A-(epichlorohydrin) epoxy resin. In someembodiments, the uncured bisphenol epoxy resin is2,2′[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane epoxyresin. In some embodiments the uncured bisphenol epoxy resin comprisesbisphenol-A-(epichlorohydrin) epoxy resin,2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxiraneepoxy resin, or combinations of these. In some embodiments, the diluenthas the structure R¹—O—CH₂—(C₂H₃O), wherein R¹ is an alkyl having from12 to 14 carbon atoms. In some embodiments the diluent is oxiranemono[(C₁₂-C₁₄)-alkyloxy)methyl] derivatives. In some embodiments, thediluent is 1,6 hexanediol diglycidyl ether. In some embodiments thediluent comprises oxirane mono[(C₁₂-C₁₄)-alkyloxy)methyl] derivatives,1,6 hexanediol diglycidyl ether, or combinations of these. In someembodiments, the uncured epoxy resin system comprisesbisphenol-A-(epichlorohydrin) epoxy resin and with oxirane mono[(C₁₂-C₁₄ alkyloxy)methyl] derivatives. An exemplary epoxy resin thatcontains bisphenol-A-(epichlorohydrin) epoxy resin with oxirane mono[(C₁₂-C₁₄ alkyloxy)methyl] derivatives is Razeen® 2254, sold by JubailChemical Industries Co. (JANA), Saudi Arabia. In some embodiments, theuncured epoxy resin system comprises2,2′[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane epoxyresin and 1,6 hexanediol diglycidyl ether. An exemplary epoxy resin thatcontains2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxiraneepoxy resin with the reactive diluent 1,6 hexanediol diglycidyl ether isRazeen® 2253, sold by Jubail Chemical Industries Co. (JANA), SaudiArabia.

In some embodiments, the LCM precursor may comprise from 50 wt. % to 90wt. % epoxy resin portion based on the total weight of the LCMprecursor. In some embodiments, the LCM precursor may comprise from 50wt. % to 90 wt. %, from 50 wt. % to 88 wt. %, from 50 wt. % to 86 wt. %,from 50 wt. % to 84 wt. %, from 50 wt. % to 82 wt. %, from 50 wt. % to80 wt. %, from 50 wt. % to 78 wt. %, from 50 wt. % to 76 wt. %, from 50wt. % to 74 wt. %, from 50 wt. % to 70 wt. %, from 50 wt. % to 68 wt. %,from 50 wt. % to 66 wt. %, from 50 wt. % to 64 wt. %, from 50 wt. % to60 wt. %, from 50 wt. % to 55 wt. %, 55 wt. % to 90 wt. %, from 55 wt. %to 88 wt. %, from 55 wt. % to 86 wt. %, from 55 wt. % to 84 wt. %, from55 wt. % to 82 wt. %, from 55 wt. % to 80 wt. %, from 55 wt. % to 78 wt.%, from 55 wt. % to 76 wt. %, from 55 wt. % to 74 wt. %, from 55 wt. %to 70 wt. %, from 55 wt. % to 68 wt. %, from 55 wt. % to 66 wt. %, from55 wt. % to 64 wt. %, from 55 wt. % to 62 wt. %, from 55 wt. % to 60 wt.%, from 60 wt. % to 90 wt. %, from 60 wt. % to 88 wt. %, from 60 wt. %to 86 wt. %, from 60 wt. % to 84 wt. %, from 60 wt. % to 82 wt. %, from60 wt. % to 80 wt. %, from 60 wt. % to 78 wt. %, from 60 wt. % to 76 wt.%, from 60 wt. % to 74 wt. %, from 60 wt. % to 70 wt. %, from 70 wt. %to 100 wt. %, from 70 wt. % to 95 wt. %, from 70 wt. % to 90 wt. %, from70 wt. % to 88 wt. %, from 70 wt. % to 86 wt. %, from 70 wt. % to 84 wt.%, from 70 wt. % to 82 wt. %, from 70 wt. % to 80 wt. %, from 70 wt. %to 78 wt. %, from 70 wt. % to 76 wt. %, from 70 wt. % to 74 wt. %, from74 wt. % to 95 wt. %, from 74 wt. % to 90 wt. %, from 74 wt. % to 88 wt.%, from 74 wt. % to 86 wt. %, from 74 wt. % to 84 wt. %, from 74 wt. %to 82 wt. %, from 74 wt. % to 80 wt. %, from 74 wt. % to 78 wt. % from80 wt. % to 100 wt. %, from 80 wt. % to 95 wt. %, from 80 wt. % to 90wt. %, from 80 wt. % to 88 wt. %, from 80 wt. % to 86 wt. %, from 80 wt.% to 84 wt. %, from 84 wt. % to 100 wt. %, from 84 wt. % to 95 wt. %,from 84 wt. % to 90 wt. %, from 84 wt. % to 88 wt. %, or from 84 wt. %to 86 wt. %. epoxy resin portion based on the total weight of the LCMprecursor.

As previously discussed in this disclosure, the LCM precursor comprisesa curing agent to cure the uncured bisphenol epoxy resin. As usedthroughout this disclosure, the term “cure” or “curing,” when used inthe context of the epoxy resin systems, may refer to the process ofcross-linking the epoxy resin, which is in a liquid form initially, witha curing agent to form a semi-solid, solid, foamed semi-solid, or foamedsolid cured epoxy resin. The curing agent may comprise at least oneamine group. Curing agents with amine functional groups may comprise,but are not limited to, at least one of an amine, polyamine, amineadduct, polyamine adduct, alkanolamine, phenalkamines, or combinationsof these. Amine or polyamine curing agents may comprise, but are notlimited to, aliphatic amines, cycloaliphatic amines, modifiedcycloaliphatic amines such as cycloaliphatic amines modified bypolyacrylic acid, aliphatic polyamines, cycloaliphatic polyamines,modified polyamines such as polyamines modified by polyacrylic acid, oramine adducts such as cycloaliphatic amine adducts or polyamine adducts.

In some embodiments, the curing agent may comprise at least one oftrimethyl hexamethylene diamine (TMD), diethylenetriamine (DETA),triethylenetetramine (TETA), meta-xylenediamine (MXDA),aminoethylpiperazine (AEP), tetraethylenepentamine (TEPA),polyetheramine, isophoronediamine (IPDA), diethyltoluenediamine (DETDA),polyoxypropylene diamine, or combinations of these. In one or moreembodiments, the curing agent may comprise at least one of DETA, DETDA,polyoxypropylene diamine, or combinations of these. In one or moreembodiments, the curing agent may be an ethyleneamine. The LCM precursormay comprise a plurality of curing agents.

The curing agent may be an amine curing agent having an amine value thatenables the amine curing agent to fully cure the epoxy resin system. Theamine value of a curing agent gives the active hydrogen (NH) content ofan amine curing agent. The amine value is expressed as the weight inmilligrams of potassium hydroxide (KOH) needed to neutralize the NH in 1gram of the amine curing agent. In some embodiments, the curing agentmay have an amine value of from 250 milligrams of KOH per gram (mgKOH/g) to 1700 mg KOH/g, from 250 mg KOH/g to 1650 mg KOH/g, from 250 mgKOH/g to 1600 mg KOH/g, from 450 mg KOH/g to 1700 mg KOH/g, from 450 mgKOH/g to 1650 mg KOH/g, from 450 mg KOH/g to 1600 mg KOH/g, from 650 mgKOH/g to 1700 mg KOH/g, from 650 mg KOH/g to 1650 mg KOH/g, or from 650mg KOH/g to 1600 mg KOH/g. The amine value may be determined bytitrating a solution of the curing agent with a dilute acid, such as a 1N solution of hydrochloric acid (HCl). The amine value may then becalculated from the amount of HCl needed to neutralize the amine in thesolution according to Equation 1 (EQU. 1):

$\begin{matrix}\frac{V_{HCl}*N_{HCl}*{MW}_{KOH}}{W} & {{EQU}.1}\end{matrix}$

where V_(HCl) is the volume in milliliters of HCl needed to neutralizethe amine, N_(HCl) is the normality of HCl used to titrate the amine,MW_(KOH) is the molecular weight of KOH in grams per mole, and W is theweight in grams of the curing agent sample titrated. The amine number ofthe known pure amine curing agent may be calculated from Equation 2(EQU. 2):

$\begin{matrix}\frac{1000*{MW}_{KOH}}{{MW}_{{curing}{agent}}} & {{EQU}.2}\end{matrix}$

where MW_(KOH) is the molecular weight of KOH in grams per mole, andMW_(curing agent) is the molecular weight of the curing agent in gramsper mole.

The amine curing agent may have an amine hydrogen equivalent weight(AHEW) that enables the amine curing agent to fully cure the epoxy resinsystem. The AHEW of an amine curing agent refers to the grams of theamine curing agent containing 1 equivalent of amine. The AHEW of anamine curing agent may be calculated by dividing the molecular weight ofthe amine curing agent in grams per mole by the number of activehydrogens per molecule. In some embodiments, the curing agent may be anamine curing agent having an AHEW of from 20 grams (g) to 120 g, from 20g to 115 g, from 20 g to 110 g, from 20 g to 100 g, from 40 g to 120 g,from 40 g to 115 g, from 40 g to 110 g, from 40 g to 110 g, from 60 g to120 g, from 60 g to 115 g, or from 60 g to 110 g determined according tothe methods previously described in this disclosure.

In some embodiments, the LCM precursor may comprise from 1 wt. % to 30wt. % curing agent based on the total weight of the LCM precursor beforecuring, such as within 30 minutes of adding the curing agent to the LCMprecursor. In one or more embodiments, the LCM precursor may comprisefrom 1 wt. % to 30 wt. %, from 1 wt. % to 25 wt. %, from 1 wt. % to 20wt. %, from 1 wt. % to 15 wt. %, from 1 wt. % to 10 wt. %, from 2 wt. %to 30 wt. %, from 2 wt. % to 25 wt. %, from 2 wt. % to 20 wt. %, from 2wt. % to 15 wt. %, from 2 wt. % to 10 wt. %, from 5 wt. % to 30 wt. %,from 5 wt. % to 25 wt. %, from 5 wt. % to 20 wt. %, from 5 wt. % to 15wt. %, from 5 wt. % to 10 wt. %, from 10 wt. % to 30 wt. %, from 10 wt.% to 25 wt. %, from 10 wt. % to 20 wt. %, or from 10 wt. % to 15 wt. %curing agent based on the total weight of the LCM precursor beforecuring, such as within 30 minutes of adding the curing agent to the LCMprecursor. An exemplary curing agent is RAZEENCURE® 931, a linearethylene amine containing two primary nitrogens and one secondarynitrogen, sold by Jubail Chemical Industries Co. (JANA), Saudi Arabia.

In some embodiments, the LCM precursor comprises surfactants. In someembodiments, the surfactant is in an aqueous solution. In someembodiments, the surfactant is from 10 wt. % to 50 wt. % by weight ofthe aqueous solution. For example, the surfactant can be from 10 wt. %to 15 wt. %, from 10 wt. % to 20 wt. %, from 10 wt. % to 25 wt. %, from10 wt. % to 30 wt. %, from 10 wt. % to 35 wt. %, from 10 wt. % to 40 wt.%, from 10 wt. % to 45 wt. %, from 10 wt. % to 50 wt. %, from 20 wt. %to 25 wt. %, from 20 wt. % to 30 wt. %, from 20 wt. % to 35 wt. %, from20 wt. % to 40 wt. %, from 20 wt. % to 45 wt. %, from 20 wt. % to 50 wt.%, from 30 wt. % to 35 wt. %, from 30 wt. % to 40 wt. %, from 30 wt. %to 45 wt. %, from 30 wt. % to 50%, from 35 wt. % to 40 wt. %, from 35wt. % to 45 wt. %, from 35 wt. % to 50%, from 40 wt. % to 45 wt. %, from40 wt. % to 50 wt. %, or from 45 wt. % to 50 wt. % by weight of theaqueous solution. In some embodiments, the surfactant is an aqueoussolution containing a hydroxysultaine. In some embodiments, thesurfactant is an aqueous solution containing cocamidopropylhydroxysultaine. In some embodiments, the surfactant is a 43 wt %solution of cocamidopropyl hydroxysultaine in water. An exemplaryaqueous solution of cocamidopropyl hydroxysultaine is PETROSTEP® SB,sold by Stepan Company (Northfield, Ill., USA).

In one or more embodiments, the LCM precursor may comprise a surfactantin an amount of from 0.1% to 5% by weight of the LCM precursor beforecuring, such as within 30 minutes of adding the curing agent to the LCMprecursor. For example, the surfactant can be from 0.5% to 5% by weightof the LCM precursor such as from 0.5% to 4.5%, from 0.5% to 4%, from0.5% to 3.5%, from 0.5% to 3%, from 0.5% to 2.5%, from 0.5% to 2%, from0.5% to 1.5%, from 0.5% to 1%, from 1% to 5%, from 1% to 4.5%, from 1%to 4%, from 1% to 3.5%, from 1% to 3%, from 1% to 2.5%, from 1% to 2%,from 1% to 1.5%, from 1.5% to 5%, from 1.5% to 4.5%, from 1.5% to 4%,from 1.5% to 3.5%, from 1.5% to 3%, from 1.5% to 2.5%, from 1.5% to 2%,from 2% to 5%, from 2% to 4.5%, from 2% to 4%, from 2% to 3.5%, from 2%to 3%, from 2% to 2.5%, from 2.5% to 5%, from 2.5% to 4.5%, from 2.5% to4%, from 2.5% to 3.5%, from 2.5% to 3%, from 3% to 5%, from 3% to 4.5%,from 3% to 4%, from 3% to 3.5%, from 3.5% to 5%, from 3.5% to 4.5%, from3.5% to 4%, from 4% to 5%, from 4% to 4.5%, from 4.5% to 5%, or 0.1%,0.5%, 1%, 1.5%, 2%, 2.5%, 2.6%, 3%, 3.5%, 4%, 4.5%, or 5% by weight ofthe LCM precursor before curing, such as within 30 minutes of adding thecuring agent to the LCM precursor. In some embodiments, the LCMprecursor contains 2% to 3% surfactant by weight of the LCM precursor,before curing. In some embodiments, the LCM precursor contains 2.7%surfactant by weight of the LCM precursor before curing. In someembodiments, the surfactant is cocamidopropyl hydroxysultaine. In someembodiments, the surfactant is an aqueous solution of cocamidopropylhydroxysultaine.

As previously discussed, the LCM precursor comprises one or more carbondioxide gas-generating compounds. As used throughout this disclosure,the term “carbon dioxide gas-generating compound” may refer to amaterial, compound, or formulation that results in the generation ofcarbon dioxide gas. The carbon dioxide gas-generating compounds may besodium bicarbonate, baking powder, or other compounds. Without beingbound by theory, it is believed that sodium bicarbonate decomposes uponheating and generates carbon dioxide gas as a reaction product. In someembodiments, any acid may be added with the carbon dioxidegas-generating compound to the LCM precursor. Additionally, it isbelieved that sodium bicarbonate decomposes in the presence of acid. Forexample, mixing sodium bicarbonate in the presence of acetic acidproduces carbonic acid. Carbonic acid may subsequently decompose togenerate carbon dioxide gas. Without being bound by any particulartheory, it believed that the addition of acid with sodium bicarbonatemay result in a LCM precursor that may form a foamed LCM compositionwithout additional heating of the LCM precursor, or heating to a lowertemperature compared to LCM precursors in the absence of an acid.

In some embodiments, the LCM precursor may comprise from 1 wt. % to 30wt. % carbon dioxide gas-generating compounds based on the total weightof the LCM precursor before curing, such as within 30 minutes of addingthe curing agent to the LCM precursor. In one or more embodiments, theLCM precursor may have from 1 wt. % to 30 wt. %, from 1 wt. % to 25 wt.%, from 1 wt. % to 20 wt. %, from 1 wt. % to 15 wt. %, from 1 wt. % to10 wt. %, from 2 wt. % to 30 wt. %, from 2 wt. % to 25 wt. %, from 2 wt.% to 20 wt. %, from 2 wt. % to 15 wt. %, from 2 wt. % to 10 wt. %, from5 wt. % to 30 wt %, from 5 wt. % to 25 wt %, from 5 wt. % to 20 wt %,from 5 wt. % to 15 wt %, from 5 wt. % to 10 wt %, from 10 wt. % to 30 wt%, from 10 wt. % to 25 wt %, from 10 wt. % to 20 wt %, from 10 wt. % to15 wt %, from 15 wt. % to 30 wt %, from 15 wt. % to 25 wt %, from 15 wt.% to 20 wt %, from 20 wt. % to 30 wt %, from 20 wt. % to 25 wt %, orfrom 25 wt. % to 30 wt % carbon dioxide gas-generating compounds basedon the total weight of the LCM precursor before curing, such as within30 minutes of adding the curing agent to the LCM precursor.

The LCM precursor may be used for treating lost circulation zones in awellbore under a range of different downhole conditions. For example, insome embodiments, the LCM precursor may be adapted to different downholeconditions by changing the concentrations of the epoxy resin, the curingagents, the one or more surfactants, or the one or more carbon dioxidegas-generating compounds in the LCM precursor to modify the specificgravity, viscosity, mechanical properties, curing time, volume, or otherproperties of the LCM compositions.

The LCM precursor may have a cure time that enables the LCM precursor tobe transferred into the lost circulation zone in the formation beforethe buildup of viscosity during curing causes transfer problems, such asinability to pump the LCM precursor.

The curing time of the epoxy resin system may be inversely proportionalto the amount of curing agent in the LCM precursor. For example,increasing the amount of the curing agent in the LCM precursor maydecrease the curing time of the LCM precursor. The LCM precursor maycomprise an amount of curing agent capable of curing the LCM precursorto a semi-solid state in a cure time of less than or equal to 48 hours,less than or equal to 24 hours, less than or equal to 12 hours, or evenless than or equal to 8 hours.

As used in this disclosure, the term “semi-solid” refers to a state ofthe epoxy resin system that is between a liquid and a solid and in whichthe cured epoxy polymers exhibit greater elasticity and flexibilitycompared to an epoxy resin cured all the way to a rigid solid. In thesemi-solid state, the LCM compositions containing the epoxy resinsystems may be easily deformed but may return to shape upon releasingthe deforming force. The LCM compositions that include the epoxy resinsystem cured to a semi-solid or solid state are capable of treating alost circulation zone, such as a high-injectivity lost circulation zone.

Without intending to be bound by any particular theory, it is believedthat that the presence of carbon dioxide and surfactants in the LCMprecursor during the curing process results in a cured foamed LCMcomposition that has an increased volume compared to the uncured LCMprecursor.

In one or more embodiments, the LCM precursor may comprise an amount ofsurfactant necessary for the extent of foaming desired in the LCMcomposition. For instance, the amount of surfactant used in the LCMprecursor may be increased to increase the extent of foaming in the LCMcomposition. Alternatively, the amount of surfactant used in the LCMprecursor may be decreased to decrease the extent of foaming in the LCMcomposition.

The extent of foaming in the LCM composition may be controlled byvarying the concentration of the carbon dioxide gas-generating compoundin the LCM precursor. The concentration of the carbon dioxidegas-generating compound in the LCM precursor may be increased ordecreased depending on the characteristics of the lost circulation zone,such as but not limited to the porosity, fluid loss rate, injectivityfactor, dimensions of the lost circulation zone, or combinations ofthese. As a non-limiting example, the concentration of carbon dioxidegas-generating compound in the LCM precursor may be increased for lostcirculation zones having greater porosity or greater fluid loss rate andmay be decreased for lost circulation zones having less porosity orlesser fluid loss rate.

In some embodiments, the LCM precursor may have a weight ratio of thecarbon dioxide gas-generating compound to the surfactant of about 5:1 toabout 1:5, such as about 4:1 to about 1:4, about 3:1 to about 1:3, about2:1 to about 1:2, or about 1:1. For example, the LCM precursor may havea weight ratio of the carbon dioxide gas-generating compound to thesurfactant of about 5:1, about 4.5:1, about 4:1, about 3.5:1, about 3:1,about 2.5:1, about 2:1, about 1.5:1, about 1:1, about 1:1.5, about 1:2,about 1:2.5, about 1:3, about 1:3.5, about 1:4, about 1:4.5, or about1:5. In some embodiments, the LCM precursor may have a ratio of carbondioxide gas-generating compound to surfactant of about 2:1. In someembodiments, the carbon dioxide gas-generating compound is sodiumbicarbonate. In some embodiments, carbon dioxide gas-generating compoundis baking powder. In some embodiments, the surfactant is a sultaine. Insome embodiments, the surfactant is cocamidopropyl hydroxysultaine. Insome embodiments, the composition contains baking soda andcocamidopropyl hydroxysultaine in a weight ratio of about 2:1.

Also provided herein is a method of servicing a lost circulation zone.In some embodiments, the lost circulation zone is fluidly connected to awellbore. The method may comprise providing the LCM precursor within aportion of a subterranean formation containing the lost circulationzone; and forming the foamed LCM composition.

In some embodiments of the methods of the present disclosure, the LCMprecursor is introduced into a subterranean formation containing thelost circulation zone using a pump.

In some embodiments, the LCM compositions may be more chemicallyresistant than conventional cement compositions. For example, the fluidsfrom the subterranean formation, such as hydrocarbon gases, crude oil,or produced water, may include hydrogen sulfide gas (H₂S), which ishighly corrosive. In some embodiments, the LCM compositions of thepresent disclosure may be resistant to corrosion caused by H₂S gaspresent in fluids in the subterranean formation.

The LCM compositions may be capable of withstanding a wide range oftemperatures and pressures without failing or substantiallydeteriorating, which would allow liquids or gases to penetrate into orthrough the LCM compositions. For example, the LCM composition may beeffective for lost circulation prevention at ranging temperatures, asdescribed herein. The LCM compositions may be used at temperaturesranging from about 150° F. to about 450° F., such as about 150° F. toabout 400° F., about 150° F. to about 350° F., about 150° F. to about300° F., about 150° F. to about 250° F., about 150° F. to about 200° F.,about 170° F. to about 400° F., about 170° F. to about 350° F., about170° F. to about 300° F., about 170° F. to about 250° F., about 170° F.to about 200° F., about 175° F. to about 450° F., about 175° F. to about400° F., about 175° F. to about 350° F., about 175° F. to about 300° F.,about 175° F. to about 250° F., about 175° F. to about 200° F., about200° F. to about 450° F., about 200° F. to about 400° F., about 200° F.to about 350° F., about 200° F. to about 300° F., about 200° F. to about250° F., about 250° F. to about 450° F., about 250° F. to about 400° F.,about 250° F. to about 350° F., about 250° F. to about 300° F., about300° F. to about 450° F., about 300° F. to about 400° F., about 300° F.to about 350° F., about 350° F. to about 450° F., about 350° F. to about400° F., or about 400° F. to about 450° F. In some embodiments, thefoamed LCM compositions are formed at elevated temperatures, such as ator above about 170° F. or at or above about 200° F., or up to about 450°F. In some embodiments, the foamed LCM composition forms at atemperature below 85° F. In some embodiments, the foamed LCM compositionforms at a temperature below 95° F. In some embodiments, the foamed LCMcomposition does not form at a temperature below 95° F. In someembodiments, the foamed LCM composition does not form at a temperaturebelow 150° F. In some embodiments, the foamed LCM composition does notform at a temperature below 170° F. For instance, the addition of anacid to the LCM precursor may reduce the temperature at which a foamedLCM composition may form. Without being bound by any particular theory,it is believed that an increase in the concentration of an acid in theLCM precursor may lower the temperature at which the carbon dioxidegas-generating compound may decompose to produce carbon dioxide.

In some embodiments, a method of treating a lost circulation zone in awellbore may include positioning an LCM composition according to thepresent disclosure in the lost circulation zone to produce a barrieroperable to prevent wellbore fluids from passing into the lostcirculation zone. The LCM composition may be a foam comprising a gasphase and a liquid phase. The LCM composition may comprise a curedbisphenol epoxy resin, wherein the cured bisphenol epoxy resin is areaction product of an uncured bisphenol epoxy resin, a curing agent,and optionally, a diluent. The LCM composition may comprise one or moresurfactants positioned at the interface of the liquid phase and the gasphase of the foam, and carbon dioxide in the gas phase of the foam,wherein the carbon dioxide is a reaction product of one or more carbondioxide gas-generating compounds. The cured bisphenol epoxy resin mayinclude at least one of bisphenol-A-epichlorohydrin epoxy resin, or2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane. Theepoxy resin may include one or more than one of the epoxy resinsdescribed in this disclosure. The surfactants may include one or aplurality of the surfactants described in this disclosure.

In some embodiments, the use of the LCM compositions of the presentdisclosure decreases the amount of lost circulation material required toplug vugular zones as compared to traditional lost circulation materialsthat are not able to expand and adapt in volume. Lost circulation zonessuch as vugular zones are difficult to plug due to the high volume oflost circulation materials required to plug them. In the case ofconventional, non-foaming epoxy resins used as lost circulationmaterials, a high volume of conventional and resin material would berequired to plug vugular zones with non-foaming LCM compositions. Thus,in some embodiments of the provided methods, the foamed LCM compositionsof the present disclosure cure the losses in vugular zones while usingless material than traditional LCM compositions.

In some embodiments, the LCM composition may include any otherconstituent, property, or characteristic previously described in thisdisclosure for the LCM compositions. The lost circulation zone may beisolated from the other portions of the wellbore by the cured LCMcomposition.

The wellbore forms a pathway capable of permitting both fluids andapparatus to traverse between the surface and the hydrocarbon-bearingformation. Besides defining the void volume of the wellbore, thewellbore wall also acts as the interface through which fluid cantransition between the subterranean formation and the interior of thewell bore. The wellbore wall can be unlined (that is, bare rock orformation) to permit such interaction with the formation or lined, suchas by a tubular string, so as to prevent such interactions.

The wellbore may include at least a portion of a fluid conduit thatlinks the interior of the wellbore to the surface. The fluid conduitconnecting the interior of the wellbore to the surface may be capable ofpermitting regulated fluid flow from the interior of the wellbore to thesurface and may permit access between equipment on the surface and theinterior of the wellbore. Example equipment connected at the surface tothe fluid conduit includes pipelines, tanks, pumps, compressors, andflares. The fluid conduit may be large enough to permit introduction andremoval of mechanical devices, including but not limited to tools, drillstrings, sensors, and instruments, into and out of the interior of thewell bore.

The wellbore may be drilled using a drill string in the presence of adrilling fluid. While drilling the wellbore, the drilling operation mayencounter a lost circulation zone. When a lost circulation zone isencountered during drilling, fluids in the wellbore flow from thewellbore into the subterranean formation, resulting in loss of thesefluids. These fluids can include but are not limited to drilling fluids,sealing compositions, spacer fluids, wash fluids, pre-flush fluids, ordisplacement fluids. In some instances, lost circulation may be causedby the natural state of the subterranean formation through which thedrilling passes. For example, the subterranean formation may benaturally fractured or may be an unconsolidated formation, such as butnot limited to gravel, sand, pea, or combinations of these. Thesubterranean formation may also include caves, caverns, tunnels, orother voids in the formation capable of receiving fluids from thewellbore. Alternatively, in other circumstances, the hydrostaticpressure of the fluids in the wellbore may be greater than the fracturegradient of the subterranean formation, which may cause at least somebreakdown of the pores in the formation. If the pores in the formationbreakdown, then the pores may become large enough to reduce theresistance to flow of fluids into and through the pores, which mayresult in the formation receiving fluids from the wellbore instead ofresisting the flow of these fluids into the formation.

The method may further include introducing a spacer fluid into the lostcirculation zone before introducing the LCM precursor. As usedthroughout the disclosure, “spacer fluid” may refer to a fluid utilizedto space apart any two other materials utilized in well production. Insome embodiments, the LCM precursor may not be compatible with thedrilling fluid or other fluid present in the wellbore. The spacer fluidmay displace the fluid present in the wellbore before the LCM precursoris pumped into the well bore. The spacer fluid may maintain the LCMprecursor separate from the fluids already present in the wellbore toreduce or prevent degradation of the LCM precursor, fluid in thewellbore or both. The spacer fluid may be compatible with the fluidspresent in the wellbore as well as the LCM precursor. The method mayfurther include introducing a displacement fluid after the LCM precursorto displace the LCM precursor into the lost circulation zone. Thedisplacement fluid may push the LCM precursor into the lost circulationto increase the amount of LCM precursor in the lost circulation zone andreduce curing of the LCM precursor in the wellbore, in particular incompleted portions of the wellbore closer to the surface. In someembodiments, a packer may be utilized to direct placement of the LCMcomposition into the lost circulation zone. The method may furtherinclude drilling through at least a portion of the barrier formed by theLCM composition to continue drilling the wellbore. In some embodiments,one or more subsequent treatments with the LCM precursor may beconducted to fully treat the lost circulation zone.

EXAMPLES

The various embodiments of the present disclosure will be furtherclarified by the following examples. The examples are illustrative innature, and should not be understood to limit the embodiments of thepresent disclosure. In these examples two epoxy resins were evaluatedfor use in the embodiments described in the present disclosure. Table 1is subsequently included in this disclosure and provides across-reference for the epoxy resins utilized.

TABLE 1 Cross-Reference of Epoxy Resins Epoxy Resin ID Epoxy Resin NameResin 1 bisphenol-A-epichlorohydrin epoxy resin with the reactivediluent oxirane mono [(C₁₂-C₁₄)-alkyloxy)methyl] derivatives Resin 22,2′-[(1-methylethylidene)bis(4,1- phenyleneoxymethylene)]bisoxiraneepoxy resin with the reactive diluent 1,6 hexanediol diglycidyl ether.

Example 1

In example 1, the effect the carbon dioxide gas-generating compound andsurfactant have on the bisphenol epoxy resin upon curing is observed.Specifically, two bisphenol epoxy resin samples are prepared: Example1A, which includes 15 grams of a modified liquid bisphenol epoxy resin,2.25 grams of a curing agent (commercially available as RAZEENCURE® 931from Jana Company), 0.5 grams of a surfactant, and 1 gram of bakingsoda; and Example 1B, which includes 15 grams of the modified liquidbisphenol epoxy resin and 2.25 grams of the curing agent. The modifiedliquid bisphenol epoxy resin is commercially available as Razeen® LR2254 from Jana Company. Razeen® LR 2254 is a low viscosity epoxy resinbased on bishpenol A and modified with an aliphatic monoglycidyl ether;Razeen® LR 2254 is bishphenol-A-(epichlorhydrin) epoxy resin (84-86%;CAS-No. 25068-38-6) with the reactive diluent oxiranemono[(C₁₂₋₁₄)-alkyloxy)methyl] derivatives (14-18%; CAS-No. 68609-97-2)(Resin 1). RAZEENCURE® 931 is diethylenetriamine (DETA). The surfactantis an aqueous solution of 50 wt. % cocoamidopropyl hydroxysultainecommercially available as PETROSTEP® SB from Stepan Company. Each sampleis stirred for 2 minutes using a glass rod and then placed in a waterbath at a temperature of 170 degrees Fahrenheit (° F.) (76.7° C.) for 2hours. The volume of each sample after curing is reported in Table 2.

TABLE 2 Observations after Cure Time for Resin 1 Quantity QuantitySample Curing Quantity of of Curing Quantity of of Baking ID Resin agentResin (g) Agent (g) Surfactant (g) Soda (g) Observation 1A Resin 1 DETA15 2.25 0.5 1 Volume of 42 mL after 2 hrs 1B Resin 1 DETA 15 2.25 0 0Volume of 17.5 mL after 2 hrs

As shown in Table 2 and FIG. 1 , after 2 hours in the 170° F. waterbath, the control (Sample 1B) does not exhibit an increase in volume ofthe cured (hardened) resin. FIGS. 2A and 2B show the sample 1A resincontaining the surfactant and baking soda just after mixing (FIG. 2A)and after 2 hours in the 170° F. (76.7° C.) water bath (FIG. 2B). Theresin has significantly expanded and the volume increases from 17.5 mLto 42 mL after 2 hours as compared to the control sample after 2 hoursin the same conditions.

Example 2

In example 2, the effect the carbon dioxide gas-generating compound andsurfactant have on the bisphenol epoxy resin upon curing is alsoobserved. Specifically, two bisphenol epoxy resin samples are prepared:Example 2A, which includes 15 grams of a modified liquid bisphenol epoxyresin, 2.25 grams of a curing agent (commercially available asRAZEENCURE 931 from Jana Company), 0.5 grams of a surfactant, and 1 gramof baking soda; and Example 2B, which includes 15 grams of the modifiedliquid bisphenol epoxy resin and 2.25 grams of the curing agent. Themodified liquid bisphenol epoxy resin is commercially available asRazeen® LR 2253 from Jana Company. Razeen® LR 2253 is a low viscosityepoxy resin based on bishpenol A and modified with an aliphaticdiglycidyl ether; Razeen® LR 2253 is2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane(70-90 wt. %; CAS-No. 1675-54-3) with the reactive diluent 1,6hexanediol diglycidyl ether (10-30 wt. %; CAS-No. 933999-84-9) (Resin2). RAZEENCURE 931 is diethylenetriamine (DETA). The surfactant is anaqueous solution of 50 wt. % cocoamidopropyl hydroxysultainecommercially available as PETROSTEP® SB from Stepan Company. Each sampleis allowed to cure at a constant temperature of 150° F. for 2 hours. Thevolume of each sample after curing is reported in Table 3.

TABLE 3 Observations after Cure Time for Resin 2 Quantity QuantitySample Curing Quantity of of Curing Quantity of of Baking ID Resin agentResin (g) Agent (g) Surfactant (g) Soda (g) Observation 2A Resin 2 DETA15 2.25 0.5 1 Volume of 42.5 mL after 2 hrs 2B Resin 2 DETA 15 2.25 0 0Volume of 17 mL after 2 hrs

As shown in Table 3, after 2 hours in the 150° F. water bath, thecontrol (Sample 2B) did not exhibit an increase in volume of the cured(hardened) resin. On the contrary, the example (Sample 2A) significantlyexpanded and the volume increased from 17 mL to 42.5 mL after 2 hours ascompared to the control sample after 2 hours in the same conditions.

According to an aspect, either alone or in combination with any otheraspect, a method of treating a lost circulation zone includespositioning a cured lost circulation material composition in the lostcirculation zone of a subterranean natural resource well to produce abarrier operable to mitigate wellbore fluids from passing into the lostcirculation zone. The cured lost circulation material composition is afoam comprising a gas phase and a liquid phase. The cured lostcirculation material composition includes a cured bisphenol epoxy resin,one or more surfactants positioned at the interface of the liquid phaseand the gas phase of the foam, and carbon dioxide in the gas phase ofthe foam. The cured bisphenol epoxy resin is a reaction product of abisphenol epoxy resin system comprising uncured bisphenol epoxy resin,one or more curing agents, and optionally, a diluent. The carbon dioxideis a reaction product of one or more carbon dioxide gas-generatingcompounds.

According to a second aspect, either alone or in combination with anyother aspect, the cured bisphenol epoxy resin comprisesbisphenol-A-epichlorohydrin epoxy resin,2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane, orcombinations of these.

According to a third aspect, either alone or in combination with anyother aspect, the bisphenol epoxy resin system comprises the diluent,wherein the diluent has the structure R¹—O—CH₂—(C₂H₃O), and wherein R¹is an alkyl having from 12 to 14 carbon atoms.

According to a fourth aspect, either alone or in combination with anyother aspect, the bisphenol epoxy resin system comprises the diluent,and wherein the diluent is 1,6 hexanediol diglycidyl ether.

According to a fifth aspect, either alone or in combination with anyother aspect, one or more of the surfactants is a hydroxysultaine.

According to a sixth aspect, either alone or in combination with anyother aspect, one or more of the surfactants is cocoamidopropylhydroxysultaine.

According to a seventh aspect, either alone or in combination with anyother aspect, a method of treating a lost circulation zone furtherincludes combining the bisphenol epoxy resin system, the surfactants,and the carbon dioxide gas-generating compounds to form a lostcirculation material precursor.

According to an eighth aspect, either alone or in combination with anyother aspect, the uncured bisphenol epoxy resin and the optional diluentof the bisphenol epoxy resin system define an epoxy resin portion of thelost circulation material precursor. The lost circulation materialprecursor comprises from 60 weight percent to 90 weight percent of theepoxy resin portion based on the total weight of the lost circulationmaterial precursor.

According to a ninth aspect, either alone or in combination with anyother aspect, the lost circulation material precursor comprises from 5weight percent to 15 weight percent of the one or more curing agentsbased on the total weight of the lost circulation material precursor.

According to a tenth aspect, either alone or in combination with anyother aspect, the lost circulation material precursor comprises from 1weight percent to 5 weight percent surfactants based on the total weightof the lost circulation material precursor.

According to a eleventh aspect, either alone or in combination with anyother aspect, the lost circulation material precursor comprises from 5weight percent to 15 weight percent carbon dioxide gas-generatingcompounds based on the total weight of the lost circulation materialprecursor.

According to a twelfth aspect, either alone or in combination with anyother aspect, the curing agent comprises trimethyl hexamethylene diamine(TMD), diethylenetriamine (DETA), triethylenetetramine (TETA),meta-xylenediamine (MXDA), aminoethylpiperazine (AEP),tetraethylenepentamine (TEPA), polyetheramine, isophoronediamine (IPDA),beta-hydroxyalkyl amide (HAA), diethyltoluenediamine (DETDA),polyoxypropylene diamine, or combinations of these.

According to a thirteenth aspect, either alone or in combination withany other aspect, the carbon dioxide gas-generating compound comprisessodium bicarbonate.

According to a fourteenth aspect, either alone or in combination withany other aspect, the epoxy resin system includes the diluent, theuncured bishphenol epoxy resin is bisphenol-A-epichlorohydrin epoxyresin, the diluent is oxirane mono [(C₁₂-C₁₄)-alkyloxy)methyl]derivatives, and one or more of the surfactants is cocoamidopropylhydroxysultaine.

According to a fifteenth aspect, either alone or in combination with anyother aspect, the epoxy resin system includes the diluent, the uncuredbishphenol epoxy resin is2,2′[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane, thediluent is 1,6 hexanediol diglycidyl ether, and one or more of thesurfactants is cocoamidopropyl hydroxysultaine.

It will be apparent to persons of ordinary skill in the art that variousmodifications and variations can be made without departing from thescope of the present disclosure. Since modifications, combinations,sub-combinations, and variations of the disclosed embodiments, whichincorporate the spirit and substance of the present disclosure, mayoccur to persons of ordinary skill in the art, the scope of the presentdisclosure should be construed to include everything within the scope ofthe appended claims and their equivalents.

It is noted that one or more of the following claims utilize the term“where” or “in which” as a transitional phrase. For the purposes ofdefining the present technology, it is noted that this term isintroduced in the claims as an open-ended transitional phrase that isused to introduce a recitation of a series of characteristics of thestructure and should be interpreted in like manner as the more commonlyused open-ended preamble term “comprising.” For the purposes of definingthe present technology, the transitional phrase “consisting of” may beintroduced in the claims as a closed preamble term limiting the scope ofthe claims to the recited components or steps and any naturallyoccurring impurities. For the purposes of defining the presenttechnology, the transitional phrase “consisting essentially of” may beintroduced in the claims to limit the scope of one or more claims to therecited elements, components, materials, or method steps as well as anynon-recited elements, components, materials, or method steps that do notmaterially affect the novel characteristics of the claimed subjectmatter.

The transitional phrases “consisting of” and “consisting essentially of”may be interpreted to be subsets of the open-ended transitional phrases,such as “comprising” and “including,” such that any use of an open endedphrase to introduce a recitation of a series of elements, components,materials, or steps should be interpreted to also disclose recitation ofthe series of elements, components, materials, or steps using the closedterms “consisting of” and “consisting essentially of.” For example, therecitation of a composition “comprising” components A, B, and C shouldbe interpreted as also disclosing a composition “consisting of”components A, B, and C as well as a composition “consisting essentiallyof” components A, B, and C.

Any quantitative value expressed in the present application may beconsidered to include open-ended embodiments consistent with thetransitional phrases “comprising” or “including” as well as closed orpartially closed embodiments consistent with the transitional phrases“consisting of” and “consisting essentially of.”

As used in the Specification and appended Claims, the singular forms“a”, “an”, and “the” include plural references unless the contextclearly indicates otherwise. The verb “comprises” and its conjugatedforms should be interpreted as referring to elements, components orsteps in a non-exclusive manner. The referenced elements, components orsteps may be present, utilized or combined with other elements,components or steps not expressly referenced.

It should be understood that any two quantitative values assigned to aproperty may constitute a range of that property, and all combinationsof ranges formed from all stated quantitative values of a given propertyare contemplated in this disclosure. The subject matter of the presentdisclosure has been described in detail and by reference to specificembodiments. It should be understood that any detailed description of acomponent or feature of an embodiment does not necessarily imply thatthe component or feature is essential to the particular embodiment or toany other embodiment. Further, it should be apparent to those skilled inthe art that various modifications and variations can be made to thedescribed embodiments without departing from the spirit and scope of theclaimed subject matter.

What is claimed is:
 1. A method of treating a lost circulation zone, themethod comprising: positioning a cured lost circulation materialcomposition in the lost circulation zone of a subterranean naturalresource well to produce a barrier operable to mitigate wellbore fluidsfrom passing into the lost circulation zone, wherein the cured lostcirculation material composition is a foam comprising a gas phase and aliquid phase, and wherein the cured lost circulation materialcomposition comprises: a cured bisphenol epoxy resin, wherein the curedbisphenol epoxy resin is a reaction product of a bisphenol epoxy resinsystem comprising uncured bisphenol epoxy resin, one or more curingagents, and optionally, a diluent; one or more surfactants positioned atthe interface of the liquid phase and the gas phase of the foam; andcarbon dioxide in the gas phase of the foam, wherein the carbon dioxideis a reaction product of one or more carbon dioxide gas-generatingcompounds.
 2. The method of claim 1, wherein the cured bisphenol epoxyresin comprises bisphenol-A-epichlorohydrin epoxy resin,2,2′-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane, orcombinations of these.
 3. The method of claim 1, wherein the bisphenolepoxy resin system comprises the diluent, wherein the diluent has thestructure R¹—O—CH₂—(C₂H₃O), and wherein R¹ is an alkyl having from 12 to14 carbon atoms.
 4. The method of claim 1, wherein the bisphenol epoxyresin system comprises the diluent, and wherein the diluent is 1,6hexanediol diglycidyl ether.
 5. The method of claim 1, wherein one ormore of the surfactants is a hydroxysultaine.
 6. The method of claim 1,wherein one or more of the surfactants is cocoamidopropylhydroxysultaine.
 7. The method of claim 1, further comprising combiningthe bisphenol epoxy resin system, the surfactants, and the carbondioxide gas-generating compounds to form a lost circulation materialprecursor.
 8. The method of claim 7, wherein: the uncured bisphenolepoxy resin and the optional diluent of the bisphenol epoxy resin systemdefine an epoxy resin portion of the lost circulation materialprecursor; and the lost circulation material precursor comprises from 60weight percent to 90 weight percent of the epoxy resin portion based onthe total weight of the lost circulation material precursor.
 9. Themethod of claim 7, wherein the lost circulation material precursorcomprises from 5 weight percent to 15 weight percent of the one or morecuring agents based on the total weight of the lost circulation materialprecursor.
 10. The method of claim 7, wherein the lost circulationmaterial precursor comprises from 1 weight percent to 5 weight percentsurfactants based on the total weight of the lost circulation materialprecursor.
 11. The method of claim 7, wherein the lost circulationmaterial precursor comprises from 5 weight percent to 15 weight percentcarbon dioxide gas-generating compounds based on the total weight of thelost circulation material precursor.
 12. The method of claim 1, whereinthe curing agent comprises trimethyl hexamethylene diamine (TMD),diethylenetriamine (DETA), triethylenetetramine (TETA),meta-xylenediamine (MXDA), aminoethylpiperazine (AEP),tetraethylenepentamine (TEPA), polyetheramine, isophoronediamine (IPDA),beta-hydroxyalkyl amide (HAA), diethyltoluenediamine (DETDA),polyoxypropylene diamine, or combinations of these.
 13. The method ofclaim 1, wherein the carbon dioxide gas-generating compound comprisessodium bicarbonate.
 14. The method of claim 1, wherein: the epoxy resinsystem comprises the diluent; the uncured bishphenol epoxy resin isbisphenol-A-epichlorohydrin epoxy resin; the diluent is oxirane mono[(C₁₂-C₁₄)-alkyloxy)methyl] derivatives; and one or more of thesurfactants is cocoamidopropyl hydroxysultaine.
 15. The method of claim1, wherein: the epoxy resin system comprises the diluent; the uncuredbishphenol epoxy resin is2,2′[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane; thediluent is 1,6 hexanediol diglycidyl ether; and one or more of thesurfactants is cocoamidopropyl hydroxysultaine.